From 1588def91d58bf70afe1acf9fc0331fa26e974f4 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 23 May 2018 11:51:29 +0100 Subject: afs: Mark afs_net::ws_cell as __rcu and set using rcu functions The afs_net::ws_cell member is sometimes used under RCU conditions from within an seq-readlock. It isn't, however, marked __rcu and it isn't set using the proper RCU barrier-imposing functions. Fix this by annotating it with __rcu and using appropriate barriers to make sure accesses are correctly ordered. Without this, the code can produce the following warning: >> fs/afs/proc.c:151:24: sparse: incompatible types in comparison expression (different address spaces) Fixes: f044c8847bb6 ("afs: Lay the groundwork for supporting network namespaces") Reported-by: kbuild test robot Signed-off-by: David Howells --- fs/afs/cell.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'fs/afs/cell.c') diff --git a/fs/afs/cell.c b/fs/afs/cell.c index fdf4c36cff79..80fd127239ce 100644 --- a/fs/afs/cell.c +++ b/fs/afs/cell.c @@ -341,8 +341,8 @@ int afs_cell_init(struct afs_net *net, const char *rootcell) /* install the new cell */ write_seqlock(&net->cells_lock); - old_root = net->ws_cell; - net->ws_cell = new_root; + old_root = rcu_access_pointer(net->ws_cell); + rcu_assign_pointer(net->ws_cell, new_root); write_sequnlock(&net->cells_lock); afs_put_cell(net, old_root); @@ -755,8 +755,8 @@ void afs_cell_purge(struct afs_net *net) _enter(""); write_seqlock(&net->cells_lock); - ws = net->ws_cell; - net->ws_cell = NULL; + ws = rcu_access_pointer(net->ws_cell); + RCU_INIT_POINTER(net->ws_cell, NULL); write_sequnlock(&net->cells_lock); afs_put_cell(net, ws); -- cgit v1.2.3